Biostatus and Distribution

This distinctive adventive ladybird is from Australia and was first found in Auckland in 1961. There are two subspecies, Apolinus lividigaster wallacii (Crotch) and Apolinus lividigaster lividigaster (Mulsant). Only the latter is known to be in New Zealand. It is a common ladybird in Auckland and present in Bay of Plenty and Hawkes Bay. It is found in crops, parks and gardens on trees and shrubs and other plants infested with aphids.

Conservation status: This adventive ladybird is present in parts of the North Island. It may contribute to control aphids on some native plants, and economic and ornamental plants.

Life Stages and Annual Cycle

The black and yellow adults are about 3-4 millimetres long. The head, prothorax (first part of the middle body) and elytra (wing covers) are black and covered with dense short hairs. The front lateral corners of the prothorax are a bright yellow. The front of the head of males is yellow brown, while in females it is black. The underside of the ladybird is mid brown to black. The first pair of legs are brown, while the other two pairs are dark except the feet are mid brown. Under the elytra is a pair of wings used for flying. The small head has a pair of compound eyes and two short antennae. The antennae are brown.

Female ladybirds lay creamy yellow eggs near infestations of prey. A larva hatches from each egg. There are four larval instars (stages). As the larva grows, it moults (changes skin). The newly hatched larva is a green-faun colour. The second instar larva is grey with dark tubercles. The third and fourth instar larvae are black with white dots and other pale areas and have long tubercles. These two larval instars also produce wax on their under and upper sides, and which shows up as white patches on the dorsal (top) surface of the thorax and abdomen. There are three pairs of legs. Larvae also use the tip of the abdomen for holding onto the substrate on which they are walking.

The tip of the abdomen also holds the larva to the surface during moulting both to another larval instar and to a pupa. When the fourth larval instar is fully grown, it attaches itself to a sheltered place on a plant. Before it moults into the pupa, the prepupa spreads wax in circles around the area to which it is attached. It rubs it legs on the wax areas of its body and then stretches out over the leaf and coats the surface with the wax. The pupa is mid brown with darker brown patches. It becomes covered in white wax. Adults emerge from pupae and mate. The length of time of each life stage depends on temperature, being shorter at higher temperatures.

Annual cycleThe ladybird probably overwinters as adults. Larvae have been found in spring. There are at least three generations per year in Auckland.

Walking and flyingBoth adult and larval stages of this ladybird have three pairs of legs that can be used for walking. Larvae also use the tip of the abdomen for holding onto the substrate. Adults have wings and can fly.

FeedingThe adult and larval ladybirds eat aphids. The jaws are the primarily structures used for holding and chewing the prey. Legs do not appear to be used for holding food.

Recognition

Adult yellow shouldered ladybirds are easily recognised by their black circular shape, prominent yellow area on the front lateral margins of the prothorax. The dorsal (top) surface of the adult is covered in dense fine hairs. The older larvae can be recognised by their long tubercles and dark colour with white and pale areas. The pupae are also distinctive, brown and covered in white wax. They are also surrounded by a circle of wax on the leaf.

Natural Enemies

No natural enemies of the yellow shouldered ladybird have been recorded in New Zealand, though in Australia large spotted ladybirds Harmonia conformis (Boisduval, 1835) feed on their small larvae. Richards (1980) also observed lacewing (Neuroptera) and hoverfly (Diptera: Syrphidae) larvae feeding on smaller larvae of the yellow shouldered ladybird in Australia. They are probably preyed upon by birds and spiders.

Richards (1980, see sources of information) also describes the defensive structures and behaviour of the juvenile ladybirds that deters predation.

Prey/Host

Both adults and larvae feed on aphids. They are associated with aphids on trees, shrubs and tall herbs and grasses such as sweet corn. There are unsubstantiated reports of this ladybird feeding on scale insects (Ceroplastes species) in Australia.

Additional Information

Biological control of pestsIn gardens and parks this ladybird contributes to the control of aphids on trees, shrubs and tall herbs and grasses. For example, it can be seen in colonies of the yellow aphid, Aphis nerii Boyer de Fonscolombe, 1841 (Hemiptera: Aphididae) on swan plants.

If pesticides are needed to control other pests, it is advisable to use chemicals that will have minimal harmful effects on the ladybirds or to use them at a time when the ladybirds are not present.

Diverse habits of 'ladybirds'Not all ladybirds eat insects; some feed on mites. Other species eat plant leaves and are pests especially in some tropical countries, whereas other ladybirds feed on fungi. One of these, Illeis galbula (Mulsant, 1850), from Australia, feeds on powdery mildew fungi. In New Zealand it is common on pumpkins and other cucurbits, plants that are commonly infected by powdery mildews. A plant feeding ladybird, hadda beetle (Epilachna vigintioctopunctata (Fabricius, 1775)) recently established in Auckland feeds on plants in the Solanaceae (potato family).

Defensive adaptations and behaviourRichards (1980, see sources of information) describes in detail the various defensive adaptations and behaviours of the yellow shouldered ladybird. Defensive adaptations include camouflage colouring of small larvae, frightening colouring of older larvae, long tubercles with spines, wax on larvae and pupae. Defensive behaviours include rearing up of larvae, coating wax around the pupa, and reflexive bleeding.